1. Field of the Invention
This invention relates generally to clutches for transmitting torque from a rotary driving shaft to a rotary driven shaft, and more particularly to an improved progressive engagement clutch and a compressible clutch plate assembly for the clutch.
2. Prior Art
The improved clutch and clutch plate assembly of this invention is designed primarily for use on automotive vehicles and will be described primarily in this context. It will become readily evident as the description proceeds, however, that the clutch and clutch plate assembly are capable of general use for drivably coupling any rotary driving shaft to a rotary driven shaft.
In many automotive vehicles, driving torque is transmitted from the crankshaft of the vehicle engine to the vehicle drive shaft through a clutch controlled by a clutch pedal operable by the vehicle driver. Simply stated, such a clutch includes a flywheel fixed to the engine crankshaft, a pressure plate coaxially disposed opposite the flywheel clutch facings on the adjacent sides of the flywheel and pressure plate, a clutch plate between the flywheel and pressure plate having clutch facings at opposite sides and drivably coupled to the vehicle drive shaft, and means operatively connecting the pressure plate to the clutch pedal whereby release of the of the pedal effects movement of the pressure plate toward the flywheel to a normal engaged position, and depression of the pedal retracts the pressure plate away from the flywheel to a disengaged position. When the pressure plate occupies its engaged position, the clutch plate is firmly gripped between the flywheel and pressure plate with the clutch plate clutch facings disposed in firm frictional driving contact with the flywheel and pressure plate clutch facings. The clutch plate is then drivably coupled to the flywheel for torque transmission through the clutch from the engine crankshaft to the vehicle drive shaft. When the pressure plate occupies its retracted disengaged position, the clutch plate is released from the flywheel for free rotation of the flywheel and clutch plate independently of one another, and torque transmission through the clutch is discontinued.
The prior art is replete with a vast assortment of clutches of the class described. By way of example, following is a list of patents relating to such clutches: U.S. Pat. Nos. 1,588,305; 2,091,409; 2,190,994; 2,607,445; 2,888,122; 3,180,470; 3,371,756; 3,584,718; 4,409,090; 4,180,622; 4,516,672; 4,629,047. U.S. Pat. No. 4,516,672 discloses a progressive engagement clutch.
Existing clutches suffer from various operational defects or problems. Among the more common of these are the following: chattering, particularly during clutch engagement; overheating which degrades the clutch components; glazing of the clutch facings due to overheating and slippage between the clutch facings; relatively rough clutch engagement and disengagement; undesirable stressing of a transmission coupled to the clutch; accumulation of particles and the like within the clutch which degrades its performance; and others. These defects are due, in large part, to the fact that the clutches engage relatively abruptly.